<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
async_test(t => {
  let start_length = navigation.entries().length;
  let start_index = navigation.currentEntry.index;
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  window.onload = () => t.step_timeout(() => {
    assert_equals(navigation.entries().length, start_length);

    let onnavigate_count = 0;
    navigation.onnavigate = () => onnavigate_count++;

    let key = navigation.currentEntry.key;
    navigation.navigate("#").committed
      .then(t.step_func(() => {
        assert_equals(navigation.entries().length, start_length + 1);
        assert_equals(navigation.currentEntry, navigation.entries()[start_index + 1]);
        assert_not_equals(key, navigation.currentEntry.key);
        return navigation.traverseTo(key).committed;
      }))
      .then(t.step_func(() => {
        assert_equals(navigation.entries().length, start_length + 1);
        assert_equals(navigation.currentEntry, navigation.entries()[start_index]);
        assert_equals(key, navigation.currentEntry.key);
        assert_true(navigation.canGoForward);
        return navigation.forward().committed;
      }))
      .then(t.step_func(() => {
        assert_equals(navigation.entries().length, start_length + 1);
        assert_equals(navigation.currentEntry, navigation.entries()[start_index + 1]);
        assert_true(navigation.canGoBack);
        return navigation.back().committed;
      }))
      .then(t.step_func_done(() => {
        assert_equals(navigation.entries().length, start_length + 1);
        assert_equals(navigation.currentEntry, navigation.entries()[start_index]);
        assert_equals(key, navigation.currentEntry.key);
        assert_equals(onnavigate_count, 4);
      }));
  }, 0);
}, "same-document navigate.traverseTo(), back(), and forward()");
</script>
